Qualitative risk assessment of Japanese encephalitis virus introduction and transmission in Pacific Island countries and territories
7 affiliations
- 1Frazer Institute, Faculty of Health, Medicine and Behavioural Sciences, University of Queensland, Brisbane, Queensland, Australia
- 2Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, Queensland, Australia
- 3Mosquito Control Lab, QIMR-Berghofer Medical Research Institute, Brisbane, Queensland, Australia
- 4Australian Centre for Disease Preparedness, Commonwealth Scientific and Industrial Research Organisation, Geelong, Victoria, Australia
- 5Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
- 6Department of Health Metrics Sciences, Institute for Health Metrics and Evaluation, School of Medicine, University of Washington, Seattle, Washington, United States of America
- 7Centre for Tropical Medicine and Global Health, Nuffield Department of Population Health, University of Oxford, Oxfordshire, United Kingdom
Abstract
Background: The emergence of Japanese encephalitis virus (JEV) in Australia raises questions about transmission potential across neighbouring Pacific Island countries and territories (PICs), where surveillance infrastructure and diagnostic capacity are limited. Methodology: We conducted a qualitative risk assessment of 22 PICs structured around three components: (1) ‘release assessment’, evaluating JEV introduction pathways based on geographic proximity, migratory waterbird flyway connectivity, and windborne mosquito dispersal potential; (2) ‘exposure assessment’, evaluating ecological transmission suitability based on vector and host competence and occurrence; and (3) ‘risk characterisation’, integrating release and exposure components to stratify countries into transmission risk profiles (endemic, epidemic, and low potential). Introduction potential varied across the region, with northern and western PICs having greatest connectivity to endemic regions. Ecological suitability for transmission was sufficient to support JEV transmission in 13 of the 22 PICs if introduced. Eight PICs were characterised as having endemic transmission potential (Papua New Guinea, which already has confirmed circulation, Solomon Islands, New Caledonia, Vanuatu, Fiji, Palau, Guam, and Northern Mariana Islands), based on diverse competent vector communities, high ardeid waterbird diversity, and moderate-to-high introduction potential. Five PICs (Federated States of Micronesia, Tonga, Samoa, Tuvalu, and Nauru) were characterised as having epidemic transmission potential, supported by pig densities capable of amplifying viral titres and sufficient vector diversity, but lacking ardeid populations necessary to sustain endemic cycles. The remaining nine PICs had low transmission potential due to limited vector and host communities. These risk stratifications are relative; the absolute probability of JEV establishment in any PIC remains uncertain. Conclusions: Distinct transmission profiles require differentiated public health responses, from sustained surveillance in endemic-potential settings to early detection and rapid outbreak response in epidemic-potential settings. Regional coordination through shared diagnostic networks and vaccine access pathways is critical to support preparedness before JEV becomes established across the Pacific. Author summary: Japanese encephalitis virus is a mosquito-borne pathogen that causes severe brain inflammation and is responsible for significant illness and death across Asia. Whether this virus poses a threat to Pacific Island nations has received little attention, despite the proximity of some islands to regions where the virus circulates. We assessed the potential for Japanese encephalitis virus introduction and transmission across 22 Pacific Island countries and territories by examining existing data on mosquito species, waterbird and pig populations, and connectivity to endemic regions through migratory bird flyways and geographic proximity.
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BibTeX
@article{skinner2026qualitative,
title = {{Qualitative risk assessment of Japanese encephalitis virus introduction and transmission in Pacific Island countries and territories}},
author = {Eloise B. Skinner and Amanda K. Murphy and Fan Yu and Kevin Thabo Moore and Liuyi Chen-Cao and David T. Williams and Stephan Karl and Joelyn Goi and Colleen L. Lau and Benn Sartorius},
journal = {PLOS Neglected Tropical Diseases},
year = {2026},
month = sep,
doi = {10.1371/journal.pntd.0014162},
url = {https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014162},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Qualitative risk assessment of Japanese encephalitis virus introduction and transmission in Pacific Island countries and territories
AU - Eloise B. Skinner
AU - Amanda K. Murphy
AU - Fan Yu
AU - Kevin Thabo Moore
AU - Liuyi Chen-Cao
AU - David T. Williams
AU - Stephan Karl
AU - Joelyn Goi
AU - Colleen L. Lau
AU - Benn Sartorius
PY - 2026
DA - 2026/09/03
JO - PLOS Neglected Tropical Diseases
DO - 10.1371/journal.pntd.0014162
UR - https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014162
AB - Background: The emergence of Japanese encephalitis virus (JEV) in Australia raises questions about transmission potential across neighbouring Pacific Island countries and territories (PICs), where surveillance infrastructure and diagnostic capacity are limited. Methodology: We conducted a qualitative risk assessment of 22 PICs structured around three components: (1) ‘release assessment’, evaluating JEV introduction pathways based on geographic proximity, migratory waterbird flyway connectivity, and windborne mosquito dispersal potential; (2) ‘exposure assessment’, evaluating ecological transmission suitability based on vector and host competence and occurrence; and (3) ‘risk characterisation’, integrating release and exposure components to stratify countries into transmission risk profiles (endemic, epidemic, and low potential). Introduction potential varied across the region, with northern and western PICs having greatest connectivity to endemic regions. Ecological suitability for transmission was sufficient to support JEV transmission in 13 of the 22 PICs if introduced. Eight PICs were characterised as having endemic transmission potential (Papua New Guinea, which already has confirmed circulation, Solomon Islands, New Caledonia, Vanuatu, Fiji, Palau, Guam, and Northern Mariana Islands), based on diverse competent vector communities, high ardeid waterbird diversity, and moderate-to-high introduction potential. Five PICs (Federated States of Micronesia, Tonga, Samoa, Tuvalu, and Nauru) were characterised as having epidemic transmission potential, supported by pig densities capable of amplifying viral titres and sufficient vector diversity, but lacking ardeid populations necessary to sustain endemic cycles. The remaining nine PICs had low transmission potential due to limited vector and host communities. These risk stratifications are relative; the absolute probability of JEV establishment in any PIC remains uncertain. Conclusions: Distinct transmission profiles require differentiated public health responses, from sustained surveillance in endemic-potential settings to early detection and rapid outbreak response in epidemic-potential settings. Regional coordination through shared diagnostic networks and vaccine access pathways is critical to support preparedness before JEV becomes established across the Pacific. Author summary: Japanese encephalitis virus is a mosquito-borne pathogen that causes severe brain inflammation and is responsible for significant illness and death across Asia. Whether this virus poses a threat to Pacific Island nations has received little attention, despite the proximity of some islands to regions where the virus circulates. We assessed the potential for Japanese encephalitis virus introduction and transmission across 22 Pacific Island countries and territories by examining existing data on mosquito species, waterbird and pig populations, and connectivity to endemic regions through migratory bird flyways and geographic proximity.
SN - 1935-2735
ER -